1. Field of the Invention
The present invention relates to a wafer heat-treatment system and a wafer heat-treatment method and, more particularly, to a lamp-heating single-wafer processing heat-treatment system and a lamp-heating single-wafer processing heat-treatment method that processes a single wafer by a film forming process to form an oxide and oxynitride film on a wafer or by an annealing process.
2. Background Art
Referring to FIG. 3 showing a conventional single-wafer heat-treatment system, i.e., a wafer heat-treatment system, there are shown a wafer 1, a processing chamber 2 in which a wafer 1 is processed by a high-temperature heat-treatment process, a gas inlet 2a through which a gas is supplied into the processing chamber 2, a gas outlet 2b through which a gas is exhausted from the processing chamber 2, walls 2c for separating the inner atmosphere of the processing chamber 2 from outside, heating lamps 5, and reflecting plates 4 for reflecting light emitted by the heating lamps 5.
The wafer heat-treatment system shown in FIG. 3 processes the wafer 1 by a high-temperature heat-treatment process having the following steps. A carrying robot, not shown, carries the wafer 1 through a gate, not shown, formed the wall 2c into the processing chamber 2. A shutter, not shown, is closed to close the gate so that the processing chamber 2 is sealed. Then, an inert gas, such as nitrogen, or an oxidizing gas, such as oxygen gas, is supplied through the gas inlet 2a into the processing chamber 2 and, at the same time, initial gas in the chamber is exhausted from the processing chamber 2 through the gas outlet 2b to replace initial gas with the inert gas.
Subsequently, the heating lamps 5 are turned on. Part of light emitted by the heating lamps 5 travel directly through the walls 2c of quartz or the like and part of light emitted by the heating lamps 5 is reflected by the reflecting plates 4 and the reflected light travels through the walls 2c. The wafer 1 is heated for a predetermined time by the energy of the light transmitted through the walls 2c to diffuse an impurity in the wafer 1 or to form a film on the surface of the wafer 1.
After the wafer 1 has been processed by the high-temperature heat-treatment process for the predetermined time, power supply to the heating lamp 5 is stopped and the wafer 1 is begun to cooled. Heat of the wafer 1 is dissipated to outside of the processing chamber 2 through the atmosphere in the processing chamber 2 and the temperature of the wafer 1 decreases. Upon the drop of the temperature of the wafer 1 to several hundreds degrees centigrade, the carrying robot carries the wafer 1 out of the processing chamber 2 through the gate.
Requisite conditions on the depth of junctions have progressively become severe with the miniaturization of semiconductor devices. To meet the requisite conditions on the depth of junctions, an impurity must be doped to a shallow region by using low energy and the diffusion of the impurity must be controlled by limiting thermal budget to the least extent when activating the impurity. Therefore, the reduction of time necessary for the wafer heat-treatment system to carry out the high-temperature heat-treatment process and the cool down process is a very important problem relating to the quality of the device.
In view of the recent high demand for semiconductor devices, the reduction of time necessary for the wafer heat-treatment system to carry out the high-temperature heat-treatment process, including heat up process and soak process, and the cool down process is a very important problem affecting improvement in device performance.
Nevertheless, the foregoing conventional wafer heat-treatment system is subject to various restrictions in shortening time necessary for carrying out the high-temperature heat-treatment process and the cool down process.
Theoretically, time necessary for completing the high-rate heating up process can be reduced by supplying higher power to the heating lamps or increasing the number of the heating lamps to increase the quantity of energy supplied into the processing chamber per unit time. However, an increase in the power supplied to the heating lamps increases running costs and reduces productivity. Thus, the increase in power consumption is improper. Time necessary for completing the soak process can be reduced by shortening a setting time for heat treatment recipe.
Time necessary for completing the cool down process can be reduced by positively dissipating heat from the processing chamber heated at a high temperature. However, heat cannot be efficiently dissipated because the atmosphere surrounding the wafer, the walls of the processing chamber and a lamp housing holding the heating lamps are heated.
The present invention has been made to solve the foregoing problems and it is therefore an object of the present invention to provide a wafer heat-treatment system and a wafer heat-treatment method using comparatively simple equipment and capable of processing a wafer by a desired heat-treatment process in a short time.
According to one aspect of the present invention, a wafer heat-treatment system for processing a wafer by a high-temperature heat-treatment process and cooling the heat-treated wafer, comprises walls surrounding a closed space placing the wafer and having a hollow sealing a gas therein, and a pressure-regulating unit connecting to the hollow for regulating pressure in the hollow.
According to another aspect of the present invention, in a wafer heat-treatment method, a wafer, which is in a closed space surrounded by walls each having a hollow, is processed by a high-temperature heat-treatment process. The heat-treated wafer which is in the closed space is cooled after the high-temperature heat-treatment process. Pressure in the hollows of the walls is regulated.
Other and further objects, features and advantages of the invention will appear more fully from the following description.